耕作制度对稻田土壤有机碳季节变化的影响——以海南省定安县为例

Effects of tillage systems on seasonal changes of paddy soil organic carbon:Taking Ding’an county,Hainan Province as an example

为了解耕作制度对稻田土壤有机碳时间变化的影响,选择了海南省定安县4种不同耕作制度下的稻田(一熟制、二熟制、三熟制和撂荒地)为研究对象,对比分析其表层土壤在2019年冬季(1月)、春季(4月)、夏季(7月)和秋季(10月)的有机碳和易氧化有机碳含量差异。结果表明,研究区稻田土壤有机碳含量在四个季节都表现为二、三熟制高,一熟制和撂荒地低,且在春季和夏季差异较大,夏季差异最为显著。各耕作制度下稻田土壤有机碳含量年内变化不明显。研究区不同耕作制度下稻田土壤易氧化有机碳含量都在春季时最高,一熟制和二熟制稻田土壤易氧化有机碳含量在土壤总有机碳中的占比年内变化明显,三熟制和撂荒地易氧化有机碳占比则较稳定。研究区稻田土壤有机碳和易氧化有机碳总体呈正相关关系,但由于耕作制度的不同使得其在不同季度两者之间的相关性存在一定差异。可见稻田耕作制度对土壤有机碳的累积和固定有一定影响。

In order to understand the impact of farming systems on the temporal changes of soil organic carbon,paddy under four different farming systems(one-cropping system,two-cropping system,three-cropping system and abandoned land)in Ding’an County,Hainan Province was selected as the research objects and a comparative analysis was conducted to analyze the difference in the contents of organic carbon and easily oxidized organic carbon in the surface soil of winter(January),spring(April),summer(July),and autumn(October)in 2019.The results showed that the organic carbon content of the paddy field soil in the study area was high in second and third crops,low in first crop and abandoned land in the four seasons.The difference was large in spring and summer,especially in summer.Under different tillage systems,the organic carbon content of the paddy soil did not change significantly during the year.The content of oxidizable organic carbon in the paddy soil in the study area was the highest in spring.The proportion of soil oxidizable organic carbon content in total soil organic carbon of the paddy under one-cropping system and two-cropping system changed significantly during the year,and the proportion of the three crops and the abandoned land is relatively stable.There is a positive correlation between organic carbon and easily oxidized organic carbon in the paddy soil in the study area.However,the correlation between the two is different in each season due to the different farming systems.It can be seen that the paddy field farming system has a certain effect on the accumulation and fixation of soil organic carbon.